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NCERT Solutions for Class 7 Science Chapter 10 Respiration in Organisms Exercise Questions

NCERT Solutions for Class 7 Science Chapter 10, "Respiration in Organisms," holds significant importance for 7th-grade students. These solutions have been thoughtfully prepared to present the chapter's content in an engaging and educational manner. They are expertly crafted to align with the latest CBSE syllabus, making them a valuable resource for students seeking effective exam preparation.

Access Answers to NCERT Solutions for Class 7 Science Chapter 10 Respiration in Organisms Exercise Questions

Respiration in Organisms

Question 1 :

Why do we often sneeze when we inhale a lot of dust-laden air?


Answer :

When we inhale dust-laden air, the dust irritates the nose; as a reflexive action, dust is thrown out through sneezing.


Question 2 :

Take three test tubes. Fill ¾th of each with water. Label them A, B and C. Keep a snail in test tube A, a water plant in test tube B and in C, keep both the snail and plant. Which test tube would have the highest concentration of CO2?


Answer :

Test tube A will have the highest concentration of CO2 because test tube A has a snail which expels out CO2 into the tube. Since a plant is present in both test tubes B and C, the plant will inhale CO2 to decrease CO2 concentration. Thus, there will be less concentration of CO2 in these tubes.


Question 3 :

Tick the correct answer:

(a) In cockroaches, air enters the body through

(i) lungs (ii) gills (iii) spiracles (iv) skin

(b) During heavy exercise, we get cramps in the legs due to the accumulation of

(i) carbon dioxide (ii) lactic acid (iii) alcohol (iv) water

(c) Normal range of breathing rate per minute in an average adult person at rest is

(i) 9–12 (ii) 15–18 (iii) 21–24 (iv) 30–33

(d) During exhalation, the ribs

(i) move outwards (ii) move downwards (iii) move upwards (iv) do not move at all


Answer :

a) (iii) spiracles

b) (ii) lactic acid

c) (ii) 15–18

d) (ii) move downwards


Question 4 :

Match the items in Column I with those in Column II:

Column I

Column II

(a) Yeast

(i) Earthworm

(b) Diaphragm

(ii) Gills

(c) Skin

(iii) Alcohol

(d) Leaves

(iv) Chest cavity

(e) Fish

(v) Stomata

(f) Frog

(vi) Lungs and skin


(vii) Trachea


Answer :


Column I

Column II

(a) Yeast

(iii) Alcohol

(b) Diaphragm

(iv) Chest cavity

(c) Skin

(i) Earthworm

(d) Leaves

(v) Stomata

(e) Fish

(ii) Gills

(f) Frog

(vi) Lungs and skin


Question 5 :

Mark ‘T’ if the statement is true and ‘F’ if it is false:


(i) During heavy exercise, the breathing rate of a person slows down. (T/F)


(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)


(iii) Frogs breathe through their skins as well as their lungs. (T/F)


(iv) Fishes have lungs for respiration. (T/F)


(v) The size of the chest cavity increases during inhalation. (T/F)


Answer :

i) False


ii) False


iii) True


iv) False


v) True


Question 6 :

The mountaineers carry oxygen with them because:


(a) At an altitude of more than 5 km, there is no air.


(b) The amount of air available to a person is less than that available on the ground.


(c) The temperature of air is higher than that on the ground.


(d) The pressure of air is higher than that on the ground.


Answer :

(b). The amount of air available to a person is less than that available on the ground.

Question 7 :

Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction — upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

Puzzle on respiration

(i) The air tubes of insects


(ii) Skeletal structures surrounding the chest cavity


(iii) Muscular floor of the chest cavity


(iv) Tiny pores on the surface of a leaf


(v) Small openings on the sides of the body of an insect


(vi) The respiratory organs of human beings


(vii) The openings through which we inhale


(viii) An anaerobic organism


(ix) An organism with a tracheal system


Answer :

(i) Trachea

(ii) Ribs


(iii) Diaphragm


(iv) Stomata


(v) Spiracles


(vi) Lungs


(vii) Nostrils


(viii) Yeast


(ix) Ant

Question 8 :

Why does an athlete breathe faster and deeper than usual after finishing the race?


Answer :

Athletes need a lot of energy during the race, and for the release of energy, they need a lot of oxygen; hence they breathe faster than usual after finishing the race.

Question 9 :

List the similarities and differences between aerobic and anaerobic respiration.


Answer :


  1. In both kinds of respiration, food particles are broken down to release energy

  2. Both occur inside the cells

  3. Both supply by-products


Aerobic respiration

Anaerobic respiration

Takes place in the presence of oxygen

Takes place in the absence of oxygen

End products are CO2 and H2O

End products are CO2 and alcohol

Produces a large amount of energy

The energy released is less when compared to aerobic respiration

It occurs in most plants and animals

Occurs in yeast and some bacteria

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